Disclosed herein are phase change ink compositions. More specifically, disclosed herein are phase change inks containing crystalline oxazoline compounds and amorphous polyterpene resins.
In general, phase change inks (sometimes referred to as “hot melt inks”) are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the recording substrate, either directly or via an intermediate heated transfer belt or drum, they quickly solidify to form a predetermined pattern of solidified ink drops. Phase change inks have also been used in other printing technologies, such as gravure printing, as disclosed in, for example, U.S. Pat. No. 5,496,879 and German Patent Publications DE 4205636AL and DE 4205713AL, the disclosures of each of which are totally incorporated herein by reference.
Phase change inks are desirable for ink jet printers because they remain in a solid phase at room temperature during shipping, long term storage, and the like. In addition, the problems associated with nozzle clogging as a result of ink evaporation with liquid ink jet inks are largely eliminated, thereby improving the reliability of the ink jet printing. Further, in phase change ink jet printers wherein the ink droplets are applied directly onto the final recording substrate (for example, paper, transparency material, and the like), the droplets solidify immediately upon contact with the substrate, so that migration of ink along the printing medium is prevented and dot quality is improved.
Known phase change inks generally contain components such as crystalline waxes and other materials that enable sharp and rapid phase transitions from the molten liquid state to the solid state. Many known phase change inks, however, exhibit disadvantages such as poor adhesion to paper substrates, including coated and uncoated paper substrates, poor scratch-resistance, poor image robustness, hard and brittle properties, poor ‘paper fold’ performance such as cracking and creasing of the image when the document is folded, and document offset. Further, the nonpolarity of these ink components often leads to compatibility issues with commonly available commercial dyes and pigments, resulting in the need for custom-designed colorants to ensure good solubility or dispersibility in the ink carrier and good long-term thermal stability to prevent colorant degradation or colorant migration.
Customers have also created a demand for materials that are bio-based, or derived at least partly from renewable resources. Energy and environmental policies, increasing and volatile oil prices, and public/political awareness of the rapid depletion of global fossil reserves has created a need to find sustainable materials and chemicals derived from bio-based monomers or polymers. By using bio-renewable feedstocks, such as those derived from agricultural crops or the forestry industry, manufacturers can reduce their carbon footprint and move to a carbon-neutral footprint. Bio-based polymers are also very attractive in terms of specific energy and emission savings. Using bio-based feedstock can decrease the amount of plastic targeted for landfills, help provide new sources of income for domestic agriculture, and reduce the economic risks and uncertainty associated with reliance on petroleum imported from unstable regions.
Oxazolines are a promising class of heterocyclic compounds which have been previously reported for medical, pharmaceutical, and veterinary uses, and also as additives in personal care and consumer product formulations, such as shampoos, detergents, and the like, and in oleaginous compositions such as mechanical lubricating oils and as oil and sludge dispersants. Oxazolines can be prepared efficiently in one or more reaction steps from simple starting materials, which are typically an organic carboxylic acid and a primary amino alcohol. Detailed reviews of the chemistry of oxazoles and oxazoline compounds are known, as illustrated by R. H Wiley and L. L. Bennett in Chemical Reviews, Vol. 44, pp. 447-476 (1949), and also extensively described by J. W. Cornforth in Heterocyclic Compounds, 1957, chapter 5, pp. 300-417, the disclosures of each of which are totally incorporated herein by reference. Furthermore, oxazoline derivatives being the major product from the reaction of an organic acid and amino alcohol is also known, such as disclosed by A. I. Meyers and D. L. Temple in Journal of the American Chemical Society, Vol. 92, p. 6644 (1970), the disclosure of which is totally incorporated herein by reference. Further, in European Journal of Medicinal Chemistry, 45, (2010), 1703-1716, the disclosure of which is totally incorporated herein by reference, Garrett C. Moraski et al. describe low toxicity anti-tuberculosis agents derived from o-hydroxy phenyl-oxazoline and o-hydroxy phenyl-oxazole benzyl esters.
While known materials and processes are suitable for their intended purposes, there is a need for improved phase change inks. In addition, there is a need for phase change inks that exhibit sharp and rapid phase transitions from the molten liquid state to the solid state. Further, there is a need for phase change inks that exhibit good adhesion to paper substrates, including coated and uncoated paper substrates. Additionally, there is a need for phase change inks that exhibit good scratch-resistance. A need also remains for phase change inks that exhibit good image robustness. In addition, a need remains for phase change inks that exhibit good ‘paper fold’ performance and reduced cracking and creasing of the image when the document is folded. Further, a need remains for phase change inks that exhibit document offset performance. Additionally, a need remains for phase change inks that exhibit good compatibility with commonly available colorants. In addition, there is a need for phase change inks that are suitable for ink jet printing under a variety of conditions, such as direct-to-paper (DTP) printing conditions. Further, there is a need for phase change ink compositions that are compatible with a wide variety of papers that generate high quality images on a wide variety of papers at low cost. Additionally, there is a need for phase change inks that contain at least some materials at least partly derived from bio-based or renewable resources. A need also remains for phase change inks that can be prepared at desirably low cost.